Numerous mythical creatures possessed the ability to shape shift – much fewer were able to directly copy and assume a human shape.
The Shape-Shifter, of course, was one such creature, as the only shapes he can take are those he has already seen before.
Likewise, Kitsune can take the shape of any human. Kitsune fear dogs, and rarely reside in North American, let alone Oregon.
Some fae, although unable to physically transform, can produce 'second skins' – illusions that hover over their bodies and make them appear different or human. Fae are weak to iron.
Nagas, Shahapets, and werewolves, among others, can transform into humans, but none of these creatures could deliberately mimic the appearance of another human being. Furthermore, most of these creatures cannot be found in Oregon.
Ford knew his list was not exhaustive. But it did span his experience across fifty years, and he was almost certain, then, that it covered everything he would ever see in his lifetime.
Therefore, in theory, if he found an individual who was not weak to iron, who did not fear dogs, and who specifically assumed the shape of another human being, he ought to assume it was the Shape Shifter.
But the Shape-Shifter had been trapped in the bunker for the past thirty years – if he was still alive at all.
The Shape Shifter also did not have yellow eyes.
"How could this be possible?" Ford asked to himself, more than the monster. The word echoed against empty concrete walls. Pieces of the demolished portal lay scattered in the corners of the room. Ford's boots made a low, hollow rhythm over the floor, like the slow heartbeat of a prey resigning itself to its own slaughter.
In Ford's hands was a thick leather tome, pages yellowing and corners fraying. One page screamed 'TRUST NO ONE!' while the other depicted the puzzle wheel that he, thirty years ago, dedicated far too much time to deciphering.
On the furthest wall, where the portal once stood, Ford had set up a vertical metal platform. The monster was bound to this platform by metal cuffs and chains over his small wrists, ankles, and throat. He quietly, slyly, watched as Ford paced shakily in front of him.
"Why are you doing this?" Ford demanded. "Why come back now, looking like that? Why does the devil's trap not work?"
Dipper Pines gazed back flatly.
Swerving, Ford resumed his frantic pacing, fingers combing through his frazzled hair. He needed to calm down. Bill appearing here as his nephew, it was rattling him – but the more important thing to keep in mind with Bill was to stay. Calm.
Ford exhaled, and straightened, directing his gaze straight at 'Dipper.'
"You must want something from me. The rift? It's far out your reach, Bill, and I'll never let you have it!"
'Dipper' said nothing.
"What do you want!? My mind?" Ford stepped closer. "I won't make a deal with you, so give up now. This metal plate will protect me as long as I live."
No answer. But was that a smile, curling at the corner of his lips?
Fear reached to the very tips of Ford's fingers. Dread flowed through his veins in one dawning, horrible realization.
Bill Cipher didn't want anything. It made so much sense. Bill didn't want anything because he must already have it.
The demon was already in his mind. He'd slipped in, maybe recently, maybe a long time ago, and he was playing with the wires to his brain, compromising his rationality, setting 'fear' on the highest setting, devouring his composure, leaving him jittery and irrational and on the brink of breakdown – it was all Bill, Bill the entire time.
The journal fell from his hands.
Ford staggered to a halt, envisioning Bill's claws raking through his scalp, twisting into his brain, twirling blood vessels and nerves and the organic wires of his body.
Ford's knees struck the concrete floor, his mouth opened in a wordless gasp, though he had entirely forgotten how to breathe.
He might not even be in the basement. He might not even be in reality. There was no telling. He could be anywhere, anytime, anyone. Bill could make him his puppet, dancing to his will, flitting through reality. Bill could make him nothing.
Upon him fell visions of monsters and nightmare realities, of endless, ceaseless torture; centuries passing and the birth, life, and death of empires and then humanity and Things that came after.
Some old mantra flitted into his mind, show no fear, and he remembered that once, in one reality, he hunted monsters, and that Bill betrayed him – Bill, no matter what reality, always it was ruled by Bill – and there was no stopping the terror of his might.
The world swam. His heart rumbled in his chest, quavering in time with a distant tempo.
Gravity unraveled and drifted past him in streams; textures leapt out to him in sharp, alien detail, dust specks like mountains under his fingertips, grass stroking like snakes spiraling about his ankles.
Cold cold cold. His throat closed, his muscles tensed, and he threw his head up through the surface of the water, drawing in a huge gasping breath.
He shook his head, hair soaked and sticking to his skin, and his legs began to kick.
The night sky stretched out about him; around all sides he heard the chirrup of cicadas, and… he was treading water.
Ford blinked to clear his eyes.
He was in the Gravity Falls lake. In the middle of the night. Or morning. Four or five AM based on the look of the sky. The water was freezing cold and it made his clothes cling tight to his body.
Dazed, Ford paddled to the edge of the lake and pulled himself onto the bank. Wasn't he just with Bill? Wasn't he in the basement, in the afternoon?
Flopping onto his back, Ford stared up at the sky, his clothes chilly, sodden and sticking unpleasantly to his skin.
Bill. Bill had possessed him. That was the only explanation – how he went from talking to the demon in the basement to swimming in the middle of the lake at night.
Perhaps Bill had even possessed him before this, and he hadn't remembered, hadn't known.
He wasn't safe. He needed – he needed to make it clear to himself, later, if he forgot –
Ford lunged for journal number 3, which lay not too far, and he ignored all the water that dripped from his sleeve onto the page. He needed to write a reminder -
No pen. Hastily he patted down his clothing, but nothing, nothing to write with. There was only one choice.
He yanked a pocket knife from his jacket pocket and slit open his palm – he absolutely had to write this down, else he might forget again, and forgetting was dangerous.
Frantically, he began to write: "Possessed! – Can't trust yours-"
His body came apart, particles and dust whirling up in a dizzying maelstrom of motion. In a violent, nauseating lurch, he returned, mind and body, to the basement.
The journal was gone. A bandage was wrapped about his left palm, dotted just lightly with blood.
Ford's trembling eyes met with those of the monster charading as Dipper Pines.
Bill stared back, uncomprehending.
A/N: Confused? The next chapter is from Wendy's PoV, so a lot more will make sense then!